In its simplest state, a release liner is a coated paper or film that carries sticky materials. A very common everyday use are Band-Aids®. The shiny paper that carries the Band-Aids is the release liner. And while the release liner isn’t always top of mind when you go to use that Band-Aid, release paper and films are a very necessary and complex product.
Sometimes called a ‘carrier’ or a ‘backing’ paper/film, a release liner is a product with a sticky substrate, either pressure sensitive adhesive or chemical compound such as silicone, until whatever it is carrying is ready to be released. They can be film-based, paper-based, polycoated-paper based or even have unique substrates. You can find them in every-day applications providing a barrier between a pressure-sensitive adhesive and its environment, preventing the adhesive from sticking to surfaces before its intended use. Without a release liner, an adhesive can become contaminated and lose its effectiveness, making it difficult or impossible to use.
Release liners are a critical feature of a layered construction. Because of this, they are found in several markets and applications.
- The health care markets utilize release liners for applications including wound care, transdermal drug delivery, electrodes, wearable devices, and consumer products. Medical applications can require higher levels of cleanliness in the manufacturing process, and the products often must meet special regulatory requirements. The removal of the release liner for these products is usually done by hand, often by the consumer, so consistency of release is imperative.
- Industrial applications for release liners include building & construction applications such as components in building exteriors and interiors – roofing shingles, weatherproofing and insulation products – and energy infrastructure including prepreg materials.
- The manufacturing of composites for aerospace, wind energy and performance sports utilize release papers and films to protect the surface of the prepreg material while in roll form and during the fabrication process. In these applications, having innovative materials is more important than ever due to the processing of sophisticated composite material parts.
- Release paper and film liners are used in the manufacturing of electronics for insulating and shielding electrical components as well as improving the performance of Hard Disc Drives and Flexible & Rigid Printed Circuit Boards.
- The automobile market benefits from release paper and film in applications such as PVB Safety Glass and automotive interiors but also in fuel cells and batteries for electronic vehicles.
- Pressure-sensitive tapes, labels and graphics are applications where the strength of the liner is important for adhesive coating, die-cutting and converting. The liner used in such applications have enhanced air egress technology enabling improved air evacuation.
Within recent years, there is a growing trend towards developing sustainable packaging solutions making biodegradable and easily recyclable release liners more readily available. Legislation around the world is increasingly supporting the recycling of release liner waste. One example of this is the ambitious Circular Economy Package instituted by the European Commission, setting clear targets for the reduction of waste.
Release liners are essential for ensuring that the adhesive is protected from the environment, premature adhesion is prevented, and make it possible to easily handle and transport its product. Next time you use an adhesive product, remember the release liner.